Buffering output signals in an integrated circuit (IC) application is well known. Because typical internal circuits of an IC lack sufficient current to drive external capacitances, a separate output driver is usually necessary. One common solution is to use an operational amplifier (op amp) tied in a unity gain feedback configuration, which is well known in the art. An op amp in a unity gain feedback configuration generally has good distortion characteristics.
However, employing an output driver in this manner generally suffers when the supply voltage is very low and the input common mode voltage range is restricted. Low voltage swings must be used, reducing the signal to noise ratio. Accordingly, there is a need for a low distortion buffer circuit capable of operating with a low supply voltage and a wide input voltage range.